Alternative spellings

Pronunciation

Adjective

Translations

Molds (or moulds, see
spelling differences) include all species of microscopic
fungi that grow in the
form of multicellular filaments,
called hyphae. In
contrast, microscopic fungi that grow as single cells are called
yeasts. A connected
network of these tubular branching hyphae has multiple, genetically
identical nuclei and
is considered a single organism, referred to as a colony
or in more technical terms a mycelium.

Molds reproduce through small spores, which may contain a
single nucleus or
be multinucleate. Mold spores can be asexual (the products of
mitosis) or sexual (the
products of meiosis);
many species can produce both types. Some can remain floorbourne
indefinitely, and many are able to survive extremes of temperature
and pressure.

Although molds grows on dead organic matter
everywhere in nature, their presence is only visible to the unaided
eye when mold colonies
grow. A mold colony does not comprise discrete organisms, but an
interconnected network of hyphae called a mycelium. Nutrients and in some
cases organelles may be transported throughout the mycelium. In
artificial environments like buildings, humidity and temperature
are often stable enough to foster the growth of mold colonies,
commonly seen as a downy or furry coating growing on food or
surfaces.

Some molds can begin growing at temperatures as
low as 2°C. When conditions do not enable growth, molds may remain
alive in a dormant state, within a large range of temperatures
before they die. The many different mold species vary enormously in
their tolerance to temperature and humidity extremes. Certain molds
can survive harsh conditions such as the snow-covered soils of
Antarctica, refrigeration, highly acidic solvents, and even
petroleum products such as jet fuel.

Xerophilic molds
use the humidity in the air as their only water source; other molds
need more moisture.

Uses

Food production

The koji molds are a group of Aspergillus
species, notably Aspergillus
oryzae, that have been cultured in eastern Asia for many
centuries. They are used to ferment a soybean and wheat mixture to
make soybean paste and
soy sauce. They are also
used to break down the starch in rice (saccharification)
in the production of sake
and other distilled spirits.

Health effects

Exposure to bacteria and fungus in indoor air has
emerged as a significant health problem in residential environments
as well as in occupational settings .

Mold spores can be allergenic, causing
irritations of eye, nose, throat, and lungs. In response to this,
environmental health research has yielded tests such as the
MELISA test,
which can determine whether or not a person is allergic to a
specific mold.

Molds may excrete liquids or gases; not all can
be detected by smell. Some molds generate toxic liquid or gaseous
compounds, called mycotoxins. Molds that produce
mycotoxins are
sometimes referred to as toxic molds.
Of these molds, some only produce mycotoxins under specific growing
conditions. Mycotoxins are harmful or lethal to humans and animals
when exposure is high enough.

Dermatophytes
are the parasitic fungi that cause skin infections such as Athlete's
foot and Jock Itch. Most
dermataphyte fungi take the form of a mold, as opposed to a yeast,
with appearance (when cultured) that is similar to other
molds.

Growth in buildings and homes

Mold growth in buildings can lead to a variety of
health issues. Various practices can be followed to mitigate mold
issues in buildings, the most important of which is to reduce
moisture levels that can facilitate mold growth. Removal of
affected materials after the source of moisture has been reduced
and/or eliminated may be necessary for remediation.